1. Field of the Invention
The present invention relates to a tray conveyor for conveying trays loaded with spinning bobbins and the like.
2. Description of the Prior Art
Generally, a belt conveyor is used to convey trays each carrying a spinning bobbin erected thereon. In this case, it is preferable that if a change in the direction of travel of conveyor is demanded on the way, the use of no special lift mechanism be required, that is, the same conveyor in current use be able to convey the trays in directions desired.
As shown in FIG. 3, this type of a prior-art tray conveyor is directly connected to an automatic winder 3 and a spinning frame 2 for conveying for example a full bobbin 1, and includes an ascending zone vertically rising from the spinning frame 2, a horizontal zone 5 for horizontally carrying the bobbin at the elevated level, and a descending zone 6 lowering on the automatic winder 3 side. In the ascending zone 4 and the descending zone 6, the tray T is tilted down, as if twisted, to come into engagement with the end face of the conveyor belt 7, thus moving on the belt. In these vertical zones 4 and 6, there can be provided a traffic space S for persons and cargoes.
In these vertical zones 4 and 6, as shown in FIG. 4, leaf springs 10 are installed at a specific spacing on the back side 7 (on the opposite side of the conveyor surface 8) of the conveyor belt 7 to press with their force the conveyor belt 7 against the tray T side, thus obtaining a contact pressure needed to convey the tray T held between the conveyor belt 7 and a guide 11.
The above-described prior-art tray conveyor, however, has such a problem that the leaf springs (springs) 10 of special shape will become necessary and further a larger number of parts including mounting bolts 12 and an increased manpower for assembling these parts will be required.
Since the leaf springs 10 partly exert a force to the conveyor bolt 7, a uniform contact pressure to be applied in the direction A of travel of conveyor could not be obtained. Therefore the tray conveyor requires the use of a flat belt, as the conveyor belt, having greater rigidity, becoming a very expensive equipment. Further, since the spring force becomes weak in an intermediate area between the leaf springs 10, the conveyor belt tends to deflect as indicated by an alternate long and short line in FIG. 4. Particularly when the trays T are conveyed in succession, there will occur such a problem as jamming of the trays T on the conveyor.